Axial piston multi circuit  machine

ABSTRACT

An axial multi circuit machine has a housing and centrally mounted drive shaft A cylinder barrel has a plurality cylinders with a piston placed in each cylinder In one embodiment the drive shaft rotates the cylinder barrel with respect to a stationary wedge and in another embodiment the drive shaft rotates the wedge with respect to the stationary cylinder barrel A cylinder head with a cylinder having at least one port for receiving and discharging a fluid to a first fluid circuit and a second cylinder having a second port for discharging fluid to a second fluid circuit The first and second fluid circuits are independent and can be at different pressures and flow rates Alternatively, the machine may function as a motor and receive fluid by means of one or more of the fluid circuits which in turn imparts a driving force to the drive shaft

I. CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority of U.S. provisional patent application 61/197,833 filed Oct. 29, 2008.

II. FIELD OF THE INVENTION

This invention relates to axial machines and more particularly to axial machines such as hydraulic pumps, hydraulic motors, hydraulic transformers, compressors and motors and a means for integrating multiple circuits and functions into one axial machine.

III. BACKGROUND AND SUMMARY OF THE INVENTION

Axial machines have been called upon to perform various functions such as compressors, pumps and motors in various environments. Hydraulic machines are used as hydraulic power transmission and hydraulic regulation devices which, in turn, are used in various hydraulic systems or circuits. A hydraulic transformer provides pressure and flow energy transformations within the hydraulic circuit. This is analogous to electrical transformers wherein voltages are controlled by varying the windings in the transformer to produce a desired voltage output from a different voltage input.

In past hydraulic practices, one solution to produce a desired hydraulic output is to use valves. However, this only provides pressure regulation by throttling the flow through an orifice which results in energy losses. Quite to the contrary, hydraulic transformers can provide an increase or decrease in pressure with corresponding increase or decrease in output flow. This is accomplished without incurring significant energy losses. Hydraulic transformers are typically used in conjunction with sources of power such as an electric motor and/or generator, gasoline engine, diesel engine or rotary engine, or other prime mover.

Applicant's invention is a multi-cylinder axial device, capable of use in multi circuits, which integrates separate sets of singular or multiple input/output piston cylinder ports. The cylinder ports may be fluidly interconnected with others in a set to form a fluid circuit. For ease of description, the inventive Axial Piston Multi Circuit Machine will be referred to herein as a pump/motor/transformer (“PMT”) and may embody several circuits which are isolated from each other and concentrically located about a drive shaft. The separate circuits may perform the same or different functions. This is accomplished in the axial machine by integrating separated sets of multiple input/output piston cylinder ports. Each cylinder port may communicate with others by fluidly connecting them in a set to form a fluid circuit. The PMT may therefore embody several circuits which are isolated from each other and are concentrically located about a drive shaft. A separate function of each circuit may be selected for the purpose of changing/distributing circuit pressures and flows, and/or imparting or receiving fluid thereby imparting or receiving fluid mechanical energy. This also changes the pressure and flow dynamics of each circuit. Various combinations of cylinders are available with combinations of pumps, compressors and transformers all available in one axial machine.

Furthermore, it should be understood that although at times the description refers to pumping fluid(s), it should be understood that the PMT may be used to pump liquids and/or gasses even in combinations, and the cylinders and pistons may be operating as a gas compressor rather than a liquid pump. Likewise the PMT may be used to receive liquids and/or gasses with circuit sections acting as a motor/engine and circuited cylinders and pistons may be operating as a gas expansion motor/engine and/or a hydraulic drive motor. Thus, the circuits can be liquids or gases, or a combination of both.

IV. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of the fully assembled inventive PMT.

FIG. 2 is a cross sectional view of PMT connected in dual circuit system.

FIG. 3 is a side view, partially in cross section, of the rotating cylinder barrel and cylinder head of the PMT.

FIG. 4 is a cross section taken along line 4-4 of FIG. 3 showing the location of the ports in the cylinder barrel and cylinder head at the head of the PMT.

FIG. 5 is a right end view of the rotating cylinder barrel of FIG. 3 showing the cylinder head and location of each circuit's ports as disposed radially about the shaft.

FIG. 6 is an end view looking into the cylinder barrel showing the location of the cylinders in relation to the ports in the cylinder head.

FIG. 7 is an end view of the ported end cap showing the location of the slots for a dual circuit system.

FIG. 8 is a side view in cross section taken along line 8-8 of FIG. 7 showing the ported end cap.

FIG. 9 is an end view looking into the cylinder of an alternate embodiment of the cylinder barrel showing cylinders having two different diameters and the location of the cylinders with respect to the ports in the cylinder head.

FIG. 10 is an end view of an alternate embodiment of an end cap for a PMT having three independent circuits.

FIG. 11 is an end view looking into the cylinders of another alternate embodiment of the rotating cylinder barrel showing varying diameters of three separate cylinder sets and their location with respect to the ports in the cylinder head.

V. DESCRIPTION OF THE PREFERRED EMBODIMENT

Turning to FIG. 1 there is illustrated an inventive axial piston multi circuit machine which will be referred to herein as a pump/motor/transformer (“PMT”) 26. The PMT has a casing 28. Turning to FIG. 2, the internal components of the PMT 26 are illustrated. The casing 28 has a rear or drive end 29 and a head or port end 30. Case bolts 31 extend through the main housing 28 to secure the housing and its components yet allow access to the components when required. A drive shaft 32 spins a cylinder barrel 34 containing at least two cylinders 36 and 38. The cylinder barrel 34 has a top end 35 near the port end 30. There is a piston foot 44 at one end of each of the pistons opposite the top end 35 with the other end of each piston extending into each of the cylinders 36, 38. There are pistons 40, 42 mounted in the cylinders 36, 38 that cycle or reciprocate as the cylinder barrel 34 is spun by the drive shaft 32. There is a wedge 46 at the rear or drive end 29 that causes the pistons 40, 42 to reciprocate as the cylinder barrel 34 is spun. The term “wedge” used throughout this application is meant to include a wobble plate or wedge swashplate. Integral as one piece or affixed to top end 35 of the cylinder barrel 34 is a cylinder head 50 (also seen in FIGS. 3-5). A fixed ported end cap 16 (also seen in FIG. 8) is adjacent to the rotating cylinder head 50 in a sliding and sealing relationship.

Also as seen in FIG. 2, the PMT 26 has a main bearing 62 press fitted into the drive end 29. The bearing 62 is secured with a snap ring 64. There is a drive shaft oil seal 66 that is secured within the drive end 29 around the drive shaft 32. The wedge 46 is affixed to drive end 29 by dowel pins 61 so as to preclude rotation and may have a smooth slipper plate 74 installed on its angled face.

The rotating components will now be discussed also with reference to FIG. 2. Cylinder barrel spacers 76, spring 78 and snap ring 80 are all installed into the cylinder barrel 34. Dowel thrust pins 82 are installed into holes in the foot end of the cylinder barrel 34. A ball seat 84 is mounted on the foot end of the cylinder barrel 34. The pistons 40 and 42 are inserted into each cylinder 36, 38 through the end of the cylinder barrel 34 opposite the top end 35. In the preferred embodiment there are multiple cylinders and piston assemblies positioned around the cylinder barrel 34. The dowel thrust pins 82 compress the spring 78 holding the head end of the cylinder barrel 34 and its cylinder head 50 face against the inner manifolded face of the ported end cap 16. The piston foot 44 is held firmly against the slipper plate 74 which in turn is pressed against the wedge 46.

The ported end cap 16 is positioned and sealed within the main casing 28 by O-rings 88 and any necessary retaining means. The case bolts 31 secure the casing 28 with all internal components securely fastened or positioned within.

The pistons 40, 42 move through one complete stroke with each complete rotation of the of the cylinder barrel 34. The pistons 40, 42 move within cylinders 36, 38 from a top dead center point to a bottom dead center point. In this embodiment, the stroke remains constant with no means of adjustment, thus all piston circuits of the PMT have a fixed output or intake volume based on rpm. Dynamic flow control in axial machines (usually pumps and hydraulic motors) is generally controlled by adjusting the angle of the wedge 46 which in turn varies the distance the piston travels within the cylinder, and thus the amount of fluid pumped with each stroke. Other means of active volumetric displacement output and dynamic changes of clearance volume are also possible and are generally known to those skilled in the art.

Alternative flow control means are known in the art such as rpm speed control of a fixed output device whereby fluid output variability is an outcome of selecting rpm speed. This method is used to a large extent for varying mass flow of gas compressors. An important point to consider with these variability schemes is that considering the PMT 26 incorporates multiple circuits, when mechanical or speed control variability is employed, it will affect all circuits.

In one embodiment, there are two distinct and separate fluid circuits, 15 and 17. The first circuit 15 has an output or discharge line 21 that is fluidly connected to the output of the cylinder 36. The fluid is discharged into the discharge line 21 and operates a device 18 that can be any fluidly operable device such as a fluid motor, pump or compressor. The fluid then returns via line 13 to the input of the cylinder 36.

The second circuit 17 has an output or discharge line 22 that is fluidly connected to the output of the cylinder 38. The fluid is discharged into the discharge line 22 and operates a fluid mechanical device 19 such as a motor, pump or compressor. The fluid then returns via line 23 to the input of the cylinder 38.

FIG. 5 illustrates the location of the cylinder ports in the cylinder head 50 of the PMT. As seen in FIG. 5 one set of cylinder ports 55 are placed at a radial distance “x” from the center of the drive shaft 32. The other set of cylinder ports 56 are placed a radial distance “y” from the center of the drive shaft 32. As illustrated, the distance “x” is greater than “y”, however, the cylinder ports 55 and 56 could be reversed if one had a specific preference. One set of ports 56 are fluidly connected to the first circuit 15 and the other set of ports 55 are fluidly connected to the second circuit 17. The point is that the cylinder ports for both circuits are placed at different radial distances from the center of the drive shaft 32 so that they operate independently of each other as separate compressors, motors or pumps.

In the first embodiment, as illustrated in FIGS. 2-8 there are nine cylinders comprising the two independent circuits, 15 and 17. One circuit is comprised of five cylinders and the other is comprised of four cylinders. As previously described, there are two port sets located circumferentially in the cylinder barrel 34 at different radial positions, one for each circuit. The outer port ring encompasses a series of five ports 55, and can be used to control the input/output of a pump. An inner port ring is made up of a series of four ports 56 and can be used to control the input/output of a separate pump. As can be easily ascertained, these circuit functions of two distinct pumps of the inner and outer port rings could be reversed. An example 5/4 split alignment of the cylinders 36, 38 in the cylinder barrel 34 with respect to the ports is illustrated in FIG. 6. Each of the cylinders 36 in one ring is ported through cylinder head 50 and into a respective substantially concentric porting manifold in the end cap 16 forming a circuit which is separate and independent of every other substantially concentric porting manifold circuit at a different radial location. As illustrated in FIG. 7, each porting manifold 51, 51′, 52, 52′ isolates its respective set of pistons/cylinders from other porting manifold sets of pistons/cylinders at different radial locations enabling the PMT to have multiple independent circuits for performing multiple functions. The porting manifold may be a separate component or plate integral with ported end cap 16.

As seen in FIGS. 4, 5 and 7, the multiple pistons allow fluid flow through the cylinder head 50 to access either the inner porting manifold 52, 52′ or outer porting manifold 51, 51′ in the ported end cap 16. The ported end cap 16, as shown in FIG. 7, illustrates only two separate circuits. Four inlet/outlet porting manifolds 51, 51′, 52 and 52′ are shown as machined slots in FIG. 7. One concentric pair 51, 51′ may be the inlet/outlet porting manifolds for the pumping circuit of the PMT and the other concentric pair 52, 52′ may be the inlet/outlet porting manifolds for the other pumping circuit of the PMT. For example, one porting manifold of a concentric pair may be the inlet porting manifold and the other is the outlet porting manifold for the first pumping circuit of the PMT. The other concentric pair likewise may have one slot as the inlet slot and the other as the outlet slot for the other pumping circuit of the PMT. The manifold 51 is connected to fluid discharge line 21. Manifold 51′ is connected to inlet 13. Manifold 52 is connected to fluid discharge line 22 and manifold 52′ is connected to inlet 23.

FIG. 9 illustrates an alternate embodiment for cylinder 34 integral with a cylinder head 50. In this embodiment there are five cylinders 92 of a first diameter and size. There are four cylinders 94 of a smaller diameter. The five cylinders 92 are fluidly connected as previously described to form the first circuit. The four cylinders 94 are connected to form the second circuit. The pumping characteristics of the first circuit will be different than the second circuit.

FIGS. 10 and 11 illustrate another alternate embodiment in which there are three different sized cylinders. There are four cylinders 96 that supply fluid to and are connected to form the first circuit. There are four smaller diameter cylinders 98 that supply fluid to and are connected to form the second circuit. There is a single cylinder 100 that is connected to and supplies the third circuit. Three separate sets of manifolds are machined into the end cap 16 or may be a separate plate or piece. There is an outer concentric pair 102 that is fluidly connected to the ports in cylinders 96, a central concentric pair 104 that is fluidly connected to the ports in cylinder 100, and an inner concentric pair 106 that is fluidly connected to the ports in cylinders 98. One of each concentric pair is the inlet and the other of the concentric pair is the outlet porting manifolds for the pumping circuit of the PMT. Each pair of slots is fluidly connected to a separate and segregated circuit.

The user can alter the mix of pistons for each circuit set by selecting a desired cylinder head 34 and porting configuration which changes the selected pistons/cylinders to be used in a circuit. For example, the previous nine cylinder configuration 5/4 split could be ported with an alternate cylinder head 34 configured so that six cylinders are used for one circuit with the remaining three ported for a separate circuit. Since all of the pistons drive the same common shaft there is no change in the parts count or complexity. Six piston/cylinders pump the working fluid for first the pump circuit and the remaining three piston/cylinders pump the working fluid for the second circuit. All pistons are reciprocated as they follow the angled wedge face as the cylinder is rotated. Those pistons which are used for pumping are powered by the rotating shaft and cylinders. By changing cylinder barrels or alternatively the use of selectable piston bore size cylinder sleeves with matched pistons as known in the art, it allows for different cylinders and piston/cylinder configurations to be provided by merely changing the cylinder or sleeve configuration in the barrel. One must also replace the cylinder 34 with a cylinder head 50 to one that corresponds to the desired circuit configuration so that the cylinders are properly connected to their respective circuits.

Although the axial machine was described using a drive shaft to rotate the cylinder barrel, the axial machine will work equally well when the drive shaft rotates the wedge which in turn reciprocates the pistons. As known to one skilled in the art, reed valves and manifold clusters can be used to control the input/output of the compressor cylinders. The compressor cylinders are interconnected through manifolds in ported end cap 16. In this manner separate and segregated circuits are formed such that the input/output from one set of cylinders will be fluidly connected to one circuit and the input/output from a second cylinder or group of cylinders will be connected to a second circuit. Additional circuits can also be supplied from the axial machine by controlling the valves and the output from the cylinders.

Each pumping function can be separately sized for a particular application so that in effect one PMT replaces three separate pumps. For example with three isolated pump circuits, one circuit could deliver high pressure at low flow rate, a second circuit could deliver low pressure at a higher flow rate, and a third circuit could supply another output pressure and flow rate as long as one remains within the input power constraints of the PMT. While the examples illustrated show a mix of nine pistons of varying diameter (displacement), this need not be the constricted case. The piston mix in number as well as diameter makes for a flexible variation of pistons, and consequently, mixes of isolated displacement parsing. Furthermore, the mix of pumping circuits, compressor circuits and motor circuits and be mixed as long as it remains within the capacity of the PMT.

Since the circuits and displacements are connected only through the common drive shaft, varying the drive shaft speed or RPM, proportionately varies all circuit flow rates regardless of circuit load pressures.

Thus there has been provided an axial piston multi circuit machine that provides segregated circuits for multiple functions. While the invention has been described in conjunction with a specific embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims. 

1. An axial multi circuit machine comprising: a housing, a centrally mounted drive shaft, means for rotating the drive shaft, a cylinder barrel mounted in the housing, a plurality of cylinders axially disposed in the cylinder barrel, the cylinders having a cylinder head with at least one port for receiving and discharging a fluid, a piston mounted in each of at least two of the cylinders, a wedge member mounted in the housing in driving relationship with the pistons to cause the pistons to reciprocate in their respective cylinders when the drive shaft is rotated, at least one of the cylinders being connected to a first fluid circuit for discharging a fluid at a first pressure and flow rate from the machine, at least one of the other cylinders being connected to a second fluid circuit for discharging a fluid at a second pressure and flow rate from the machine, and the first fluid circuit and the second fluid circuit being segregated from each other.
 2. The axial multi circuit machine of claim 1 wherein the cylinder barrel is removable from the machine and is replaced by a second cylinder barrel having a cylinder configuration different than the cylinder configuration of the cylinder barrel.
 3. The axial multi circuit machine of claim 1 wherein the cylinder head has at least one port disposed at a first radial distance in fluid communication with the first fluid circuit and a second port disposed at a second radial distance in fluid communication with the second fluid circuit.
 4. The axial multi circuit machine of claim 3 and further comprising an end cap mounted adjacent to the cylinder head, the end cap having a first manifold in fluid communication with the one port and a second manifold in fluid communication with the second port, the first manifold being at the first radial distance and the second manifold being at the second radial distance, the first and second manifolds being fluidly connected to the first and second fluid circuits respectively.
 5. The axial multi circuit machine of claim 1 wherein the wedge member is adjustable for changing the piston's stroke in the cylinder.
 6. The axial multi circuit machine of claim 1 wherein the wedge member is mounted on the drive shaft and rotates with the drive shaft causing the pistons to reciprocate when the wedge member is rotated with respect to the cylinder barrel.
 7. The axial multi circuit machine of claim 1 wherein the cylinder barrel is mounted on the drive shaft and rotates with the drive shaft causing the pistons to reciprocate when the cylinder barrel is rotated with respect to the wedge member.
 8. The axial multi circuit machine of claim 1 and further comprising at least a third cylinder with a piston mounted therein being connected to a third fluid circuit for discharging a fluid at a third pressure and flow rate from the machine.
 9. The axial multi circuit machine of claim 1 wherein the first and second fluid circuits have different pressures and flow rates.
 10. The axial multi circuit machine of claim 1 wherein the first and second fluid circuits have the same pressures and flow rates.
 11. The axial multi circuit machine of claim 8 wherein the first, second and third fluid circuits have different pressures and flow rates.
 12. The axial multi circuit machine of claim 1 wherein several cylinders are fluidly connected to define the first fluid circuit and at least one cylinder is fluidly connected to the second fluid circuit.
 13. The axial multi circuit machine of claim 8 wherein several cylinders are fluidly connected to the first fluid circuit and at least one cylinder is fluidly connected to the second fluid circuit, and a third cylinder is fluidly connected to the third fluid circuit.
 14. An axial multi circuit machine comprising: a housing, a centrally mounted drive shaft, means for rotating the drive shaft, a cylinder barrel mounted in the housing, a plurality of cylinders axially disposed in the cylinder barrel, the cylinders having a cylinder head with at least one port for receiving and discharging a fluid, a piston mounted in each of at least two of the cylinders, a wedge member mounted in the housing in driving relationship with the pistons, at least one of the cylinders being connected to a first fluid circuit for receiving a fluid at a first pressure and flow rate to impart a driving force to the drive shaft of the machine, at least one of the other cylinders being connected to a second fluid circuit for discharging a fluid at a second pressure and flow rate from the machine, and the first fluid circuit and the second fluid circuit being segregated from each other.
 15. The axial multi circuit machine of claim 14 wherein the cylinder head has at least one port disposed at a first radial distance in fluid communication with the first fluid circuit and at least a second port disposed at a second radial distance in fluid communication with the second fluid circuit.
 16. The axial multi circuit machine of claim 14 and further comprising at least a third cylinder having a piston mounted therein, the third cylinder connected to the second fluid circuit for discharging the fluid at the second pressure and flow rate.
 17. The axial multi circuit machine of claim 14 and further comprising at least a third cylinder having a piston mounted therein, the third cylinder connected to a third fluid circuit for discharging the fluid at a third pressure and flow rate.
 18. An axial multi circuit machine comprising: a housing, a centrally mounted drive shaft, means for rotating the drive shaft, a cylinder barrel mounted in the housing, a plurality of cylinders axially disposed in the cylinder barrel, the cylinders having a cylinder head with at least one port for receiving and discharging a fluid a piston mounted in each of at least two of the cylinders, a wedge member mounted in the housing in driving relationship with the pistons, at least one of the cylinders being connected to a first fluid circuit for receiving a fluid at a first pressure and flow rate to impart a driving force to the drive the drive shaft of the machine, at least one of the other cylinders being connected to a second fluid circuit for receiving a fluid at a second pressure and flow rate to impart a second driving force to the drive shaft of the machine, and the first fluid circuit and the second fluid circuit being segregated from each other.
 19. The axial multi circuit machine of claim 18 and further comprising at least a third cylinder having a piston mounted therein, the third cylinder connected to a third fluid circuit for discharging a fluid at a third pressure and flow rate, the third circuit being segregated from the first and second fluid circuits.
 20. The axial multi circuit machine of claim 18 wherein the cylinder head has at least one port disposed at a first radial distance in fluid communication with the first fluid circuit and a second port disposed at a second radial distance in fluid communication with the second fluid circuit.
 21. A method for providing fluid to different fluid circuits comprising: providing an axial piston multi circuit machine having at least two axial cylinders, providing two independent fluid circuits, fluidly connecting each axial cylinder to one of the two independent fluid circuits, and maintaining the fluid flow of the two independent circuits from each other.
 22. The method of claim 21 and the further steps of: providing the axial piston multi circuit machine with a third axial cylinder, providing at least a third independent fluid circuit, fluidly connecting the third fluid circuit to the third axial cylinder, and maintaining the fluid flow of the three independent circuits from each other.
 23. The method of claim 22 and the further step of providing different pressure and flow characteristics to each of the fluid circuits.
 24. The method of claim 21 and the further step of providing at least one additional cylinder fluidly connected to one of the two independent fluid circuits. 